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jackson配置类

我的jackson配置类如下，其中serializerByType(LocalDateTime.class, new LocalDateTimeSerializer()) 覆盖了@JsonFormat注解

@Configuration
public class JacksonConfiguration {public static final DateTimeFormatter optionalDateTimePattern =(new DateTimeFormatterBuilder()).appendValue(ChronoField.YEAR, 4).appendPattern("[-][/]MM[-][/]dd['T'][ ]HH[:]mm[:][ss][,SSS][.SSS]").toFormatter();;static final ZoneOffset zoneOffset = OffsetDateTime.now(ZoneId.systemDefault()).getOffset();public JacksonConfiguration() {}/*** 配置和创建ObjectMapper对象*/public static Jackson2ObjectMapperBuilder createJackson2ObjectMapperBuilder() {Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();return customizeBuilder(builder).serializerByType(LocalDateTime.class, new LocalDateTimeSerializer());}@Beanpublic Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {return (builder) -> {// serializerByType(LocalDateTime.class, new LocalDateTimeSerializer()) 覆盖了@JsonFormat注解customizeBuilder(builder).serializerByType(LocalDateTime.class, new LocalDateTimeSerializer());};}private static Jackson2ObjectMapperBuilder customizeBuilder(Jackson2ObjectMapperBuilder builder) {builder.deserializerByType(LocalDateTime.class, new LocalDateTimeDeserializer())// 将日期时间序列化为时间戳（以毫秒表示），而不是默认的日期时间字符串格式，如果已经设置了serializerByType则会失效.featuresToEnable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)// 允许将单个值解析为数组。这意味着如果 JSON 中的某个属性期望是数组类型，但实际上只有一个值，那么它也会被解析为数组。.featuresToEnable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY)// 解开包装在单个值数组中的值。这意味着如果 JSON 中的某个属性被包装在一个只有一个元素的数组中，那么它会被解包成单个值。.featuresToEnable(DeserializationFeature.UNWRAP_SINGLE_VALUE_ARRAYS);return builder;}public static final class LocalDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {public LocalDateTimeDeserializer() {}public LocalDateTime deserialize(JsonParser p, DeserializationContext context) throws IOException {// 时间戳格式if (StringUtils.isNumeric(p.getValueAsString())) {long timestamp = Long.parseLong(p.getValueAsString());// 带毫秒if (p.getValueAsString().length() == 13) {return Instant.ofEpochMilli(timestamp).atZone(JacksonConfiguration.zoneOffset).toLocalDateTime();}// 不带毫秒else {return Instant.ofEpochSecond(timestamp).atZone(JacksonConfiguration.zoneOffset).toLocalDateTime();}} else {// 2023-09-08 16:12:25 或 2023-09-08T16:12:25 或 2023-09-08 16:12:25.456 格式String dateTimeString = p.getValueAsString();if (StringUtils.isNotEmpty(dateTimeString)) {return LocalDateTime.parse(dateTimeString, optionalDateTimePattern);} else {return null;}}}}public static final class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {public LocalDateTimeSerializer() {}public void serialize(LocalDateTime value, JsonGenerator gen, SerializerProvider serializers)throws IOException {gen.writeNumber(value.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());}}
}

实体类

当我在LocalDateTime类型的属性上使用@JsonForMat失效

public class TestDTO {@JsonFormat(pattern = "yyyy/MM/dd HH:mm:ss", timezone = "GMT+8")private LocalDateTime localDateTime;public LocalDateTime getLocalDateTime() {return localDateTime;}public void setLocalDateTime(LocalDateTime localDateTime) {this.localDateTime = localDateTime;}@Overridepublic String toString() {return "TestDTO{" + "localDateTime=" + localDateTime + '}';}
}

接口

调用接口的返回值是时间戳，而不是 yyyy/MM/dd HH:mm:ss

@PostMapping("/test7")public TestDTO test7() {TestDTO testDTO = new TestDTO();testDTO.setLocalDateTime(LocalDateTime.now());return testDTO;}

返回值：

{"localDateTime": 1706086696221
}

一种解决方法

改用 @JsonSerialize 注解

@JsonSerialize(using = LocalDateTimeSerializer.class)
private LocalDateTime localDateTime;

在外面定义一个LocalDateTimeSerializer，在serialize方法中定义要输出的格式

package com.xjhqre.config;import java.io.IOException;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;public class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {public void serialize(LocalDateTime value, JsonGenerator gen, SerializerProvider serializers) throws IOException {gen.writeString(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss").format(value));}
}